A co-pending application entitled, "Shuttle Launched Triangular Space Station," Ser. No. 587,764, filed Mar. 9, 1984, and assigned to the assignee of the present application, discloses a space station constructed of triangular panels each made up of a multiplicity of collapsible and expandable modules called tetratrusses. The modules consist of a multiplicity of struts pivotally connected, certain ones of which have central hinged joints disposed so that the modules can all be collapsed into a compact bundle which can be stowed, for instance, in the payload bay of the space shuttle orbiter. The hinged joints are spring-biased so as to make the space station truss self-erecting. The hinged joints must rigidly lock the struts in coaxial alignment in the deployed position. None of the prior art has been found to be completely satisfactory for this purpose.
For instance, U.S. Pat. No. 4,365,908, to Thiboutot, discloses a spring-biased folding joint for interconnecting elongated members. The joint automatically locks in folded and expanded configurations. However, the design is very complicated and bulky and structurally weak.
Preston U.S. Pat. No. 3,563,592 discloses a lockable folding brace system including a sliding sleeve to which is attached a coiled tension spring. However, the design does not permit two tubes to lie compactly side-by-side when folded, and is not self-expanding.
Fisher U.S. Pat. No. 3,187,373 discloses a spring-loaded locking hinge mechanism which arrangement does not incorporate self-expanding springs and incorporates a spring-loaded latch instead of a four-bar linkage, as in the present invention.